Patent GB-325165-A (GB)
Title: Improvements in or relating to rotary duplicators
IPC: B41L13/04
Filed: 1929-04-17
Abstract: 325,165. Padgham, G. H. April 17, 1929. Stencil-printing apparatus.-In a rotary stencil duplicator of the kind in which sheets are fed from a pile by contacting fingers carried by a carriage reciprocated by cam mechanism operating against the action of a spring, improved means are provided for raising the sheet pile, and for tripping the machine after a given number of sheets have been operated on. The stencil drum is constructed as described in Specification 208,431. The feed contact fingers 30 are pivoted to a bar 31 of a carriage formed of two guided side members 26, 27 which are reciprocated by links 35, 36 operated by levers 45 on a shaft 47, which is fitted with an arm 50 acted on by a spring 51 tending to move the feed carriage towards the printing- cylinders, and by a cam-actuated thrust rod 55 which retracts the carriage. The fingers 30 are supported by a bar 29 on the carriage, and are set so as to make an angle of about 45‹ to the horizontal. In order to varv the frictional action, certain of the fingers may be turned on their pivots out of action. If desired, the feed mechanism may be tripped by moving all the fingers 30 out of action bv means of a lever 33 the depression of which raises a bar 34 which underlies all the fingers 30. The shaft of lever 33 is formed with a cut-away portion 59 which is normally turned towards a recess 63 in an adjustable plate 60 mounted on a slotted bracket 42 which guides the link 36, Fig. 6. When the fingers are tripped the solid portion of the shaft engages the recess 63 in the plate 60 and the carriage is prevented from moving. Mechanism is also provided for locking the carriage after a predetermined number of sheets have been fed Tripping-arrangements; impression adjustments. - The impression roller 64 is mounted in slots in the ends of lever arms 67, 68, integral with arms 70, 71 acted on by a bar 74 pressed by springs 76, 75 which embrace pins 72, 73 fitted to the arms 70, 71. To vary the printing-pressure, a cam 77 on a shaft 78 acts on the bar 74, and the shaft 78 can be rotated by a lever 81 and held in adjusted position by a pawl 80 engaging a ratchet sector 77 on shaft 78. The pawl 80 can be released by a pushbutton 82. In the normal printing operation the roller 64 is depressed at each rotation of cylinder 13 by means of a thrust rod 85 which is reciprocated by a cam 83 on the shaft 20, and is controlled by a pivoted link 90. The rod 85 acts on an arm 86 on a cross-bar 87 provided with lugs 91, 92 which press on the ends of the levers 67, 68 to depress the roller 64. In connection with the thrust rod 85 a pivoted catch 85c, Fig., 8, is provided to engage a lug 85a and hold the thrust rod depressed, and the roller 64 tripped, if the feed carriage is held out of operation. In the normal working of the machine this catch is released by a projecting plate 35<a> on the link 35 which reciprocates the feed carriage. In order to stop the feed when a predetermined number of sheets has been fed, the shaft 123 which operates the pile-raising cams 99, 100, is geared to a shaft 129 fitted with a disc 30 to which an arm 131 is adjustably clamped. This arm is set relatively to a fixed scale 133 to a number corresponding to the number of sheets to be printed, and, when the arm 131 works back to zero on this scale, a latch 144 is released and allows a pawl lever 149 to drop in the path of one of a series of notches 150 in the upper side of the link 35, and the movement of the feedcarriage is thus checked.